More in ECO:nomics

Some companies installing chargers—often with federal subsidies—wanted to get their networks up and running before initiating fees. So public charging often is free.

What's clear—about one year into the rollout of mass-produced electric cars—is that the market is "wrestling with what, if anything, to charge for charging," says
Richard Lowenthal,
founder and chief technology officer of Coulomb Technologies Inc, a Campbell, Calif., company that has built 8,600 charging points.

Coulomb runs the billing network for ChargePoint-branded chargers, but it doesn't own the equipment or set prices. Mr. Lowenthal says 80% of ChargePoint locations currently are free to use, and the rest collect fees set by location owners.

A Matter of Time

ECOtality
Inc.,
another big installer of charging stations, said in August it is dispensing free electricity at about 3,000 Blink-branded public charging points. But it expects to begin charging fees this fall.

As charging companies begin collecting fees, it looks like the most common approach will be to bill customers by length of time spent charging or by a monthly subscription fee, not the amount of electricity dispensed.

ENLARGE

NEW MODEL Soon there may be no such thing as a free charge at public stations.
ChargePoint

"Free is just not a sustainable model," says
Colin Read,
ECOtality's vice president of corporate development in San Francisco. It doesn't cover the cost of the equipment or maintenance. Nor does it nudge people to move their cars, once fully charged, he says.

Drivers often use public chargers to top off their electric car batteries while shopping, at a movie or at work. Mr. Read says cars are often left at charging points for long periods because the drivers mistakenly think no one else needs the charging point—and because it is often free.

As the number of electric cars grows, the charging companies want people to become more aware and considerate.

"We need access fees to be able to say, 'Get out of here and let someone else charge now,' " Mr. Read says.

ECOtality plans to offer a three-tiered payment structure. Drivers not registered with ECOtality will pay $2 an hour. Drivers who have registered with its Blink network will pay $1.50 an hour. And so-called Blink Plus members who also pay an annual membership fee of up to $30 will pay $1 an hour and will be allowed to reserve chargers.

ENLARGE

For a Chevy Volt or Nissan Leaf, the top-selling plug-in vehicles, paying $1 an hour for electricity works out to about 7.5 cents for each pure-electric mile driven, less than half of what it costs to fuel a car that gets 25 miles per gallon.

Fees Not Simple

Mark Duvall, an electric-vehicle expert at the Electric Power Research Institute in Palo Alto, Calif., says a typical plug-in car can soak up 3.3 kilowatt-hours of electricity an hour or 30 to 50 cents of electricity. He figures that means a price of $1 to $2 an hour is fair.

"But," he adds, "we're already seeing prices all over the place," including some that swamp the savings inherent in electricity. The highest price he's seen, he says, is $5 an hour at a charging station in Northern California.

"Anything above $2 an hour is more expensive than gasoline," says Mr. Duvall, who drives a Chevy Volt. He fears that high prices could discourage public charging and cause a fledgling network to atrophy.

Monthly Subscriptions

One New Jersey company is sidestepping the issue of how to price individual charges.

NRG Energy
Inc.
is using a subscription model for the 28 fast-charging stations that it's built in Dallas-Fort Worth and Houston, with dozens more on the way. The price is $39 a month for unlimited access to the public chargers that can fully charge most cars in half an hour or less, and $89 a month for unlimited use of fast public chargers and a slower 240-volt home charger.

Next it has its sights set on California.

Ms. Smith is a staff reporter for The Wall Street Journal in San Francisco. She can be reached at rebecca.smith@wsj.com.

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